Polyphenyl thioether lubricating compositions

ABSTRACT

Lubricating compositions comprising polyphenyl thioether, polyphenyl ethers-thioethers or mixtures thereof and containing small amounts of trichloroacetic acid have improved lubricating properties. These compositions are useful as lubricants over wide temperature ranges.

= itcd States atent Clark 1March 13, 1973 1 1 POLYPHENYL THIOETHER 232x374 1/1960 Kubie ..252/54.6 x LUBRICATINO COMPOSITIONS 3,284,355 11/1966 Papay 3,579,449 5/1971 Wann et a1. ..252/54.6 [75] Inventor: Frank S. Clark, St. Louis, Mo. [73] Assignee: Monsanto Company, St. Louis, Mo. FOREIGN PATENTS OR APPLICATIONS [22] Filed, Sep 25 1970 851,651 10/1960 Great Britain [21] App]. No.: 75,751 Primary Examiner-Daniel E. Wyman Assistant Examiner-W. Cannon U S 7 4 Att0rneyNeal E. J. E. Mauret and T.

51 Int. Cl. ..Cl0m 1/46,C10m 1/38 Black 58 F 1d fSe h ..252 45, 48.4, 49.8, 52, 54.6, 1 I 252%] 57 ABSTRACT Lubricating compositions comprising polyphcnyl References Cited thiocther, polyphenyl ethers-thioethers or mixtures UNITED STATES PATENTS th ereof and contain ng small amounts of v trichloroacetic acid have improved lubricating proper- 3,226,323 12/1965' Ste mniski ..252/54.6 X ties. These compositions are useful as lubricants over 3,510,426 5/1970 Papay ..252/49.8 X wide temperature ranges. I 2,157,873 5/1939 van Peski ..252/49.8 X 2,262,773 11/1941 Lincoln et a1. ..252/54.6 7 Claims, No Drawings POLYPHENYL THIOETHER LUBRICATING COMPOSITIONS This invention relates to improved lubricating compositions comprising polyphenyl thioethers, mixed polyphenyl ethers-thioethers and mixtures thereof, containing from three to eight aromatic groups and a small amount of trichloroacetic acid as a lubricating additive.

Polyphenyl thioethers and polyphenyl etherthioethers combinations have found wide application as functional fluids due to their excellent thermal stability and lubricity. For example they have been found to be valuable as hydraulic fluids and as lubricants in motor operation, particularly in jet engines.

Development of synthetic base stocks such as the polyphenyl thioether has provided lubricant fluids which are useful at elevated temperature such as 400 to 500F. It is known that one of the aspects in which the polyphenyl thioether base stocks are considered deficient is in their lubricating characteristics. These lubricating characterists include the load-carrying abilities and wear properties, especially under conditions of high pressures and temperatures reached in the advanced design aircraft engines. Thus there is a demand for polyphenyl thioethers having improved lubricity properties.

An object of the present invention is to provide for improved lubricating compositions employing polyphenyl thioethers, polyphenyl ether-thioethers, or mixtures thereof as base stocks.

These and other objects will become evident upon consideration of the following specification and examples.

It has now been found that compositions consisting essentially of a major amount of a polyphenyl thioether base fluid having the formula R--Y(R'-Y),.R (I) wherein R is a phenyl group, an alkyl-substituted phenyl group wherein the alkyl group contains one to four carbon atoms, an alkoxy-substituted phenyl group wherein the alkoxy group contains one to four carbon atoms or a halogenated phenyl group wherein the halogen is bromine, fluorine or chlorine, R is a phenylene group, an alkyl or alkoxy-substituted phenylene group where the alkyl group contains one to four carbon atoms or a halogenated phenylene group wherein the halogen is fluorine, bromine or chlorine, and Y is selected from oxygen and sulfur but at least one of the Ys is sulfur and n is an integer having a value of from one to six and an additive amount of trichloroacetic acid, have unusual ability to lubricate under high loads at high temperatures.

The amount of trichloroacetic acid employed in the compositions of this invention can range from 0.01 to about 0.02 percent by weight. It is preferred to employ trichloroacetic acid in the compositions of this invention in amounts of from 0.03 to 0.07 percent by weight based upon the total composition.

The improvement in lubricity characteristics achieved by the addition of the trichloroacetic acid to the polyphenyl thioether base fluid is unusual and surprising. Wear on a bearing is especially decreased at test temperatures of 600F. whereas when the base fluid is tested without the additive the lubricity of the base fluid is not sufficient and the bearing fails after a short time.

The polyphenyl thioethers employed in the composition of this invention have from three to eight benzene rings and from one to seven sulfur atoms with the sulfur atoms joining the benzene rings in chains as ether linkages.

By the term polyphenyl thioether as used herein is meant a compound or physical mixture of compounds represented by Formula I. The term includes compounds wherein all of the Ys in Formula I are sulfur. The term also includes those compounds which contain both oxygen and sulfur linkages between the benzene rings.

The compositions of this invention contain a major amount of the polyphenyl thioether base stock, i.e., at least 50 percent by weight of the total composition comprises a polyphenyl thioether. It is preferred that at least 60 percent by weight of the composition be a polyphenyl thioether base stock and even more preferred that at least 85 percent by weight of the total composition comprise a polyphenyl thioether.

The compositions of this invention can also contain from'0.01 to 10 percent by weight of the total composition of a dialkyl hydrogen phosphite extreme pressure additive. The dialkyl hydrogen phosphites useful are those wherein the alkyl groups contain from one to 12 carbon atoms. These alkyl groups are for example, methyl, ethyl, propyl, isopropyl, butyl, secbutyl-t-butyl, hexyl, decyl, isodecyl, dodecyl and the like.

Illustrations of the alkyl-substituents present in the phenyl and phenylene groups of the polyphenyl thioethers are for example, methyl, ethyl, propyl, butyl and the like. Illustrations of the alkoxy-substituents are, for example, methoxy, ethoxy, propoxy, butoxy and their isomers.

Illustrative of the polyphenyl thioethers which can be be employed as base stocks for the compositions of this invention are the bis(phenylmercapto)benzenes. For example bis(m-phenylmercapto)benzene bis(o-phenylmercapto)benzene bis(p-phenylmercapto)benzene bis(m-phenylmercaptophenyl)sulfide bis(o-phenylmercaptophenyl)sulfide bis(p-phenylmercaptophenyl)sulfide (m-phenylmercaptophenyl) (o-phenylmercaptophenyl)sulfide p-phenylmercapto-m'-phenylmercapto diphenyl sulfide o-bis(o-phenylmercaptophenylmercapto)benzene p-bis(p-phenylmercaptophenylmercapto)benzene p-bis(o-phenylmercaptophenylmercapto)benzene p-bis(m-phenylmercaptophenylmercapto)benzene m-bis(p-phenylmercaptophenylmercapto)benzene o-bis(p-phenylmercaptophenylmercapto)benzene and the like and mixtures thereof.

Illustrative of the mixed polyphenyl ether-thioether compounds which can be employed as base stocks the compositions of the this invention are for example,

o-phenylmercapto-m-phenoxy benzene p-phenylmercapto-o-phenoxy benzene m-phenoxy-p-phenylmercapto benzene o-phenylmercapto-p'-phenoxydiphenyl sulfide o-phenylmercapto-m-phenoxydiphenyl sulfide o-phenoxy-m-phenylmercaptodiphenyl sulfide m-phenoxy-p'-phenylmercaptodipheny| sulfide o-phenoxy-p'-phenylmercaptodiphenyl sulfide p-phenoxy-p-phenylmereaptodiphenyl sulfide o-phenoxy-o-phenylmereaptodiphenyl sulfide o,o-bis(phenylmercapto)diphenyl ether o-phenylmercapto-m-phenylmercaptodiphenyl ether o-phenylmercapto-p-phenylmercaptodiphenyl ether m-(m-phenylmercaptophenylmercapto) (m-phenoxyphenylmercapto)benzene [m-(m-phenylmercaptophenylmercapto)phenyl] [m-(m-phenoxyphenylmercapto )phenyl] sulfide 3-(m-phenylmercaptophenylmercapto )-3 '-(m-phenylmercaptophenoxy)diphenyl sulfide 3 ,3 '-bis( m-phenylmercaptophenylmereapto)diphen yl ether 3-( m-phenylmercaptophenylmercapto )-3 mphenoxy-phenoxy)-diphenyl sulfide 4-( m-phenylmereaptophenylmercapto)-4'-(m-phenylmercaptophenoxy)diphenyl ether 3-(m-phenylmereaptophenylmercapto)-3 '-(mphenoxyphenylmercapto)diphenyl ether 4,4'-bis( m-phenylmereaptophenoxy)diphenyl sulfide 4,4 '-bis(m-phenoxyphenylmercapto)diphenyl sulfide 3-(m-phenoxyphenylmercapto)-3'-(m-phenylmercapto phenoxy)diphenyl sulfide 3,3 -bis(m-phenylmercaptophenoxy)diphenyl ether 4-(m-phenylmereaptophenylmercapto)-4'-(mphenoxyphenoxy)diphenyl ether 3-(p-phenylmercaptophenoxy)-3'-(p-phenoxyphenoxy) diphenyl sulfide 3-(m-phenylmercaptophenoxy)-3'-(m-phenoxyphenyl-mercapto)diphenyl ether 3,3'-bis(m-phenoxyphenylmercapto)diphenyl ether and 3-(m-phenoxyphenylmercapto)-3-(mphenoxyphenoxy) diphenyl sulfide.

In addition to the foregoing compounds, the phenyl and phenylene groups of such compounds can contain substituents, such as alkyl of one to four carbon atoms, alkoxy of one to four carbon atoms and halogen such as chlorine, bromine and fluorine. Examples of such compounds are as follows:

4,4-bis(m-tolylmercapto)diphenyl ether 3,3'-bis(m-tolylmereapto)diphenyl ether 2,4-bis(m-tolylmereapto)diphenyl ether 3,4-bis(m-tolylmercapto)diphenyl ether 3,3 -bis(p-tolylmercapto)diphenyl ether 3,3'-bis(xylylmercapto)diphenyl ether 4,4-bis(xylylmercapto)diphenyl ether 3,4'-bis(xylylmercapto)diphenyl ether 3,4-bis(m-isopropylphenylmercapto)diphenyl ether 3,3-bis(m-isopropylphenylmercapto)diphenyl ether 2,4-bis(rn-isopropylphenylmercapto)diphenyl ether 3,4-bis(p-tert-butylphenylmercapto)diphenyl ether 4,4-bis(p-tert-butylphenylmercapto)diphenyl ether 3,3 -bis(p-tert-butylphenylmereapto)diphenyl ether 3,3'-bis(2,4-di-tert-butylphenylmereapto)diphenyl ether 3,3 '-bis(3-chlorophenylmercapto)diphenyl ether 4,4'-bis(3-ehlorophenylmercapto)diphenyl ether 3,3-bis(m-trifluoromethylphenylmercapto)diphenyl ether 4,4-bis(m-trifiuoromethylphenylmercapto)diphenyl ether 4 3,4'-bis(m-trifluoromethylphenylmercapto)diphenyl ether 2,3'-bis(m-trifluoromethylphenylmercapto)diphenyl ether 3,3-bis(p-trifluoromethylphenylmercapto)diphenyl 5 ether 3,3'-bis(o-trifluoromethylphenylmercapto)diphenyl ether 3,3'-bis(m-methoxyphenylmercapto)diphenyl ether 3,4-bis(m-isopropoxyphenylmercapto)diphenyl ether 3,4-bis(m-perfluorobutylphenylmercapto)diphenyl ether 2-(m-tolyloxy)-2'-phenylmercaptodiphenyl sulfide 2-(p-tolyloxy)-3'-phenylmercaptodiphenyl sulfide 2-(0-tolyloxy)-4-phenylmercaptodiphenyl sulfide 3-(m-tolyloxy)-3'-phenylmercaptodiphenyl sulfide 3-(m-tolyloxy)-4-phenylmereaptodiphenyl sulfide 4-(m-tolyloxy)-4'-phenylmercaptodiphenyl sulfide 3-xylyl0xy-4'-phenylmercaptodiphenyl sulfide 3-xylyloxy-3'-phenylmereaptodiphenyl sulfide 3-phenoxy-3'-(m-tolylmercapto)diphenyl sulfide 3-phenoxy-4'-(m-tolylmercapto)diphenyl sulfide 2-phenoxy-3'-(p-tolylmercapto)diphenyl sulfide 3-phenoxy-4-(m-isopropylphenylmereapto)diphenyl sulfide 3-phenoxy-3'-(m-isopropylphenylmereapto)diphenyl sulfide 3-m-toloxy-3'-(m-isopropylphenylmercapto)diphenyl sulfide 4-(m-trifluoromethylphenoxy)-4'-phenylmercaptodiphenyl sulfide 3-(m-trifluoromethylphenoxy)-4-phenylmercaptodiphenyl sulfide 2-(m-trifluoromethylphenoxy)-3'-phenylmercaptodiphenyl sulfide 3-(m-trifluoromethylphenoxy)-3-phenylmercaptodiphenyl sulfide 3-(p-chlorophenoxy)-3'-phenylmercaptodiphenyl sulfide 3-(m-bromophenoxy)-4'-phenylmercaptodiphenyl sulfide bis[m-(m-chlorophenoxy)phenyl]sulfide m-bis[3-(p-methylphenylmercapto)phenoxy ]benzene m-bis[3-(m-trifluoromethylphenoxy)phenylmercap to]benzene m-bis[3-(m-bromophenoxy)phenylmereapto ]benzene 3,3'-bis[m-(p-methylphenylmercapto)phenoxy] diphenyl sulfide 3,4-bis[m-(p-methylphenylmereapto)phenoxy] diphenyl sulfide 3-(p-xenyloxy)-3'-phenylmercapto diphenyl sulfide,

and the like and mixtures thereof. It is also contemplated within the scope of this invention to employ mixtures of polyphenyl ether-thioethers as base stocks.

The compositions of this invention are useful as lubricants under extreme conditions. The compositions 65 are especially useful for steel on steel lubrication.

The following examples serve to further illustrate the invention. All parts are parts by weight unless otherwise expressly set forth.

EXAMPLE 1 A polyphenyl thioether polyphenyl ether-thioether lubricant composition is prepared by combining trichloroacetic acid (0.05 grams) with 100 grams of a thioether of the following composition:

meta-bis(phenylmercapto)benzene (50 percent by weight) bis(phenoxyphenyl)sulfide (12.5 percent by weight) (phenoxyphenyl) (phenylmercaptophenyl)sulfide (23.5 percent by weight) bis(phenylmercaptophenyl)sulfide (12.65 percent by weight) 3 ring and 5 ring thioethers (1.35% by weight) and containing 0.1 percent diisopropyl hydrogen phosphite The mixture was tested in a high speed, high temperature small diameter bearing test machine employing angular-contact ball bearings. The test was conducted at 600F. under an inert nitrogen atmosphere at a speed of 44,000 rpm. The load on the apparatus was 300 pounds giving a l-lertzian stress of 200,000 p.s.i. The races and balls were constructed of M50 stainless steel while the outer race ridings were silver plated 4340 steel.

The composition of Example l was able to complete 100 hours testing with no excessive galling of the bearings or races. A sample of the same mixture of polyphenyl thioethers and a mixed polyphenyl etherthioethers containing phenyl dihydrogen phosphite but no trichloroacetic acid failed the test although the temperature was maintained at only 500F.

It will be appreciated that the compositions of this invention, in addition to the polyphenyl thioether base fluid and the trichloroacetic acid additive, may also contain other additives, such as oxidation inhibitors, rust and corrosion inhibitors, antifoaming agents, detergents, viscosity index improvers such as polymeric materials for example, polyacrylate alkyl esters, polymethacrylate alkyl esters, polyoxyalkylene compounds, polyurethanes and the like. Such additives are usually employed in amounts as low as 10 parts per mil- I While this invention has been described with respect to various specific examples and embodiments, it is understood that the invention is not limited thereto and that it can be variously practiced within the scope of the following claims.

What is claimed is:

1. A lubricant composition consisting essentially of a major amount of a polyphenyl thioether having the formula cent by weight of trichloroacetic acid.

2. composition of claim 1 wherein said trichloroacetic acid is present in amounts of from 0.03 to 0.07 parts by weight.

3. A composition of claim 1 wherein n is from 1 to 3. 4. A composition of claim 2 wherein n is from 1 to 3. 5. A lubricant composition consisting essentially of a major amount of a polyphenyl thioether having the formula wherein R is a phenyl group or a substituted phenyl group, R is a phenylene group or substituted phenylene group, in which the substituents on said phenyl and phenylene groups are halogen, alkyl or alkoxy containing from one to four carbon atoms, n is an integer of from l to 6, Y is sulfur or oxygen provided that at least one of the groups represented by Y is sulfur, and mixtures of such thioethers, from 0.01 to 0.2 percent by weight of trichloroacetic acid and from 0.1 to 10 percent by weight of a dialkyl hydrogen phosphite in which the alkyl groups contain from one to 12 carbon atoms.

6. A composition of claim 5 wherein the trichloroacetic acid is present in amounts of from 0.03 to 0.07 parts by weight and the dialkyl hydrogen phosphite is diisopropyl hydrogen phosphite.

7. A composition of claim 6 wherein n is from 1 to 3. 

1. A lubricant composition consisting essentially of a major amount of a polyphenyl thioether having the formula R- Y(R''-Y)n-R wherein R is a phenyl group or a substituted phenyl group, R'' is a phenylene group or substituted phenylene group, in which the substituents on said phenyl And phenylene groups are halogen, alkyl or alkoxy containing from one to four carbon atoms, n is an integer of from 1 to 6, Y is sulfur or oxygen provided that at least one of the groups represented by Y is sulfur, and mixtures of such thioethers and from 0.01 to 0.2 percent by weight of trichloroacetic acid.
 2. A composition of claim 1 wherein said trichloroacetic acid is present in amounts of from 0.03 to 0.07 parts by weight.
 3. A composition of claim 1 wherein n is from 1 to
 3. 4. A composition of claim 2 wherein n is from 1 to
 3. 5. A lubricant composition consisting essentially of a major amount of a polyphenyl thioether having the formula R-Y(R'' -Y)n-R wherein R is a phenyl group or a substituted phenyl group, R'' is a phenylene group or substituted phenylene group, in which the substituents on said phenyl and phenylene groups are halogen, alkyl or alkoxy containing from one to four carbon atoms, n is an integer of from 1 to 6, Y is sulfur or oxygen provided that at least one of the groups represented by Y is sulfur, and mixtures of such thioethers, from 0.01 to 0.2 percent by weight of trichloroacetic acid and from 0.1 to 10 percent by weight of a dialkyl hydrogen phosphite in which the alkyl groups contain from one to 12 carbon atoms.
 6. A composition of claim 5 wherein the trichloroacetic acid is present in amounts of from 0.03 to 0.07 parts by weight and the dialkyl hydrogen phosphite is diisopropyl hydrogen phosphite. 